#res=0
fun_one(){
  read -p "请输入 a - > " a
  read -p "请输入 b - > " b
  res=`expr $a + $b`
  echo $res
#  return  "adfasdf"
#  echo $res
#  return $res
}
d=$(fun_one)
echo "res -> $d"
#echo $res
#echo $?